The Allure of Giant Telescopes

The Polish astronomer Johannes Hevelius assembled this telescope in the city of Danzig (nowadays Gdansk) in the 17th century. The purpose of building such a large instrument was to circumvent chromatic aberration, an optical effect of refractors  resulting in color fringes around the object in view.

  Though ingenious in its design, Hevelius’s giant telescope was difficult to operate resulting in occasional observations only. This illustration, taken from a major astronomical work by Hevelius, suggests that the telescope became a local attraction nonetheless. As would happen with several other giant telescopes constructed in the coming centuries, bigger was not always better. 

 This large reflecting telescope (meaning that it captures light with a mirror) has a 40-foot tube and a 48-inch diameter primary mirror. It was made in the late 1780s under the guidance of William Herschel.  Herschel produced several smaller reflecting telescopes of high quality, some of which he used together with his sister Caroline Herschel.

 Despite all the effort put into its conception and assemblage, the 40-foot telescope did not prove substantially superior to Herschel’s smaller instruments. Nevertheless, it become a tourist attraction in England and held the title of the largest telescope in the world for decades. 

This reflecting telescope, known as the Leviathan (an allusion to a biblical monster), was set up at Birre Castle in Ireland in 1845 by William Parsons, 3rd Earl of Rosse. Parsons was one of the 19th-century “Grand Amateurs,” wealthy individuals with a passion for  astronomy and plenty of resources to invest in the production of large telescopes. 

With a  72-inch diameter mirror, the Leviathan held the status of the largest telescope in the world for decades. It allowed Parsons to discover the spiral structure of the celestial object now known as the Whirlpool Galaxy. This discovery helped pave the way to the concept that the universe contains a multitude of galaxies, and to unveiling the spiral structure of our very own galaxy, the Milky Way. 

The Great Lick Refractor, shown in the image, is named after the North-American businessman James Lick, who embarked on a quest for a monument to perpetuate his memory. After considering statues of himself and a large pyramid, Lick decided to sponsor the construction of an astronomical observatory housing the largest refracting telescope ever built. 

The tube and mount of the largest refracting telescope ever used in astronomical research are shown here in an unusual setting: the Columbian Exposition held in Chicago in 1893, which remains one of the most ambitious world fairs ever hosted.  

Conceived to mark the 400th anniversary of Columbus’s arrival in the so-called new world, it served, above all, to extoll America’s economic progress and Chicago’s ability to rebuild itself as a major urban center after the Great Fire of 1871. 

The telescope was displayed at the fair to affirm the American capabilities in the production of scientific instruments. It was later installed at Yerkes Observatory in Williams Bay, Wisconsin. The undertaking was sponsored by Charles T. Yerkes, an entrepreneur of mixed reputation who saw an opportunity to improve his public image for posterity.  

In the 20th century, large reflecting telescopes took the prominent place formerly held by refractors. Mount Wilson Observatory in California played a leading role in that regard, breaking records by harboring first a reflecting telescope with a mirror of 60 inches, and later also a 100-inch  instrument. 

This photograph was taken in 1916 and shows the lower section of the 100-inch telescope tube in transport on Mount Wilson. The assemblage of this large telescope, led by the astronomer George E. Hale, required tackling complex logistics and many technical problems, and raising large amounts of money.

Despite some defects in its primary mirror, the 100-inch telescope proved particularly important in observations that furthered our understanding of the large scale of the universe and its expansion. 

This conceptual drawing shows an observer sitting at the primary focus (the point to which light rays converge) of the 200-inch reflecting telescope of Palomar Observatory. Completed in 1947, it became the largest telescope in the world. The drawing is part of a series made by the artist, arctic explorer and amateur telescope maker, Russell Porter. 

The production of this unprecedentedly large instrument was an ambitious project that involved several teams working on specific problems, and which progressed slowly through various incidents and setbacks. By bringing all elements together in compelling depictions of what the finalized instrument was meant to look like, Russell’s images helped steer the project towards a successful completion. 

The James Webb Space Telescope, a part of whose mirror is shown in the image, is poised to take its leading place. Designed to capture infrared light, it promises to further our knowledge of the evolution of galaxies and the conditions for life beyond Earth.  

However, the fact that it is named after a NASA administrator who was purportedly involved in the discrimination of LGTBQ+ people has generated controversy, reminding us that large telescopes are not just research tools, but also monuments of science whose symbolic meanings are no less relevant than their technical capabilities.